Composition for recovering hydrocarbons

Abstract

A process for recovering hydrocarbons from a subterranean formation in which in situ combustion is first initiated in the formation by injection of air, for example, through an injection well, the injection of air is terminated, carbon dioxide or nitrogen is injected into the formation via the injection well to displace unconsumed air and in a final step a mixture of carbon monoxide and hydrogen is injected into the formation where reaction of the carbon monoxide with steam generated from the formation water forms additional hydrogen and carbon dioxide and finally hydrocarbons are recovered via a production well. Optionally, after injection of the mixture of carbon monoxide and hydrogen into the formation has been terminated the heat stored in the formation may be recovered by injecting water as a drive fluid into the formation. The injected water may contain a small amount of a sulfated interfacial tension reducer having, for example, the formula: ##STR1##

What is claimed is: 
     
       1. A fluid for use in recovering hydrocarbons from subterranean formations comprising water containing from about 0.001 to about 1.0 weight percent of an interfacial tension reducer selected from the group consisting of a compound of the formula: ##STR7## wherein r is an integer of from 2 to about 5, s is an integer of from 8 to about 60 and M is selected from the group consisting of hydrogen, sodium, potassium and the ammonium ion and a compound of the formula: ##STR8## wherein t is an integer of from 8 to about 40 and M has the same meaning as previously described. 
     
     
       2. The fluid of claim 1 wherein the said interfacial tension reducer is a compound of the formula: ##STR9## wherein r is an integer of from 2 to about 5, s is an integer of from 8 to about 60 and M is selected from the group consisting of hydrogen, sodium, potassium and the ammonium ion. 
     
     
       3. The fluid of claim 1 wherein the said interfacial tension reducer is a compound of the formula: ##STR10## wherein t is an integer of from 8 to about 40 and M is selected from the group consisting of hydrogen, sodium, potassium and the ammonium ion. 
     
     
       4. The fluid of claim 1 made alkaline with 0.01 to about 0.2 weight percent of an alkaline agent selected from the group consisting of sodium hydroxide and potassium hydroxide.